This invention relates generally to a method for heat transfer printing and embossing of man-made fabrics wherein the printing and embossing or surface texturing processes are combined in one simultaneous operation.
In the relatively new printing method called heat transfer printing, the inks are not directly deposited on the fabric or other materials to be decorated but are first printed on a paper or other perfectly flat substance. However, the composition of the ink and/or the preparation of the paper or other surface used is such that when held firmly against the fabric or other materials to be decorated, and then heated, the colors are transferred permanently to these materials. The operation is carried out on a heated transfer calender if a continuous method is used or on a heated press if a static method is applied. The heat required is in the range of 340 to 430 degrees Fahrenheit. Contact time will range generally from 5 to 40 seconds. The transfer paper is held in contact with the material to be printed by pressure means. The pressure to be applied can be as low as 1 lb. per square inch and rarely exceeds 50 lbs. per square inch.
The heat transfer printing method has two major advantages over the conventional printing methods: 1. a better registration of the designs can be obtained because all colors are transferred at the same time from the printed transfer paper, while in conventional printing one color is deposited after the other and a perfect registration is nearly impossible to obtain; and 2. the fabric inventory can be held very low because of the existing possibilities to transform at any time any quantity of white fabric into printed fabric thanks to the less expensive transfer papers held in stock.
On the other hand, the heat transfer printing system has also two major disadvantages: 1. it flattens the material to be printed. This can be explained by the contact under pressure and heat with a perfectly flat printing paper and results usually in a printed material having a "slicky hand", undesirable for many uses. Only fabrics of special composition, involving higher prices, can avoid this inconvenience. Another remedy is the use of after-treatments to improve the hand, but these are costly and result in a considerable loss of time; and 2. losses on inventory transfer paper can be high if, as a result of fashion change or other reasons, orders for a particular design or color combination diminish while important quantities of corresponding paper remains in stock.